Browsing by Author "Tsai, DP"

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Imaging properties of three dimensional aperture near-field scanning optical microscopy and optimized near-field fiber probe designs
(2004-12-01)
Chau, YF
;
Yang, TJ
;
Tsai, DP
;
電子物理學系
;
Department of Electrophysics
A series of finite difference time domain (FDTD) methods for obtaining more insight on the near-field distribution of subwavelength aperture and fiber probes are numerically investigated. The treatment of dispersive materials in a time-domain-dependent fashion is considered. Several significant factors are also considered successively, e.g., the near-field distribution of subwavelength aperture in an infinite aluminum plane with sample interactions, the characteristics between the near-field distribution and the depolarization phenomenon, different types of three-dimensional tip (noncoated and metal-coated) used to illuminate a photosensitive sample and the polarization of an incident electromagnetic field. Moreover, the FDTD designs of two types of improved probe are illustrated and a suggestion for fabricating an optimal probe is given. Our proposed structures will yield useful information and guidelines for designing high-performance near-field probes.
Near-field optics simulation of a solid immersion lens combining with a conical probe and a highly efficient solid immersion lens-probe system
(2004-04-01)
Chau, YF
;
Yang, TJ
;
Tsai, DP
;
電子物理學系
;
Department of Electrophysics
A solid immersion lens (SIL) combined with near-field probes which are the conic dielectric probe and the local metallic coating on the SIL probe is designed for optical recording by means of a three-dimensional rather than two-dimensional finite difference time domain method to gain more insight in the near-field distribution. Our computation model is realistic to match the real SIL-probe system. The optical properties of near-field distributions between the SIL probe and recording layers are investigated. A promising idea for fabricating a type of the SIL-probe system is proposed. Results of our designation of an optimal SIL-probe system can achieve higher performance (in terms of high throughput and low reflection of the light beam) for optical data storage and microscopy than the conventional metal NSOM probe or SIL used alone. (C) 2004 American Institute of Physics.
True near-field optical characters of a GaAlAs semiconductor laser diode
(1999-12-01)
Chen, SH
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Tsai, DP
;
Chen, YF
;
Ong, PM
;
電子物理學系
In this research we have taken advantage of near-field scanning optical microscopy, a recently developed technique, to test the optical nature of GaAlAs semiconductor laser diodes working at 780 nm. With this method, both the images of the topographic and the near-field intensity of the laser diodes can be simultaneously obtained. With the obtained results, we can analyze the variety of the geometric structure, the local near-field optical intensity, the propagating modes, and the near-field mode-field diameter at different working states of the laser diodes. Hereby, we can find the factors that affected the radiation cavity of the laser diode and explore its alive state. (C) 1999 American Institute of Physics. [S0034-6748(99)01112-0].